Gasoline engine choke delay devices

ABSTRACT

This invention provides means for reducing the amount of excess gasoline passed through a gasoline engine during starting. In this way the engine contribution of smog forming materials is reduced. This reduction of excess gasoline is achieved by increasing the portion of the work of compression available to evaporate gasoline. To accomplish these results, the carburetor choke on the engine is caused to pass through a cycle of opening and delayed closing, during starting, by the actions of solenoids, spring loaded dashpots, and temperature sensitive elements, acted on by ambient temperatures and current from the battery.

United States Patent 1 Firey 51 May 15,1973

1541 GASOLINE ENGINE CHOKE DELAY DEVICES [76] Inventor: Joseph Carl Firey, 1554 North East 95th Street, Seattle, Wash. 981 15 3,263,973 8/l966 Purcell ..l23/l19 F Primary ExaminerLaurence M. Goodridge [57] ABSTRACT This invention provides means for reducing the amount of excess gasoline passed through a gasoline engine during starting. in this way the engine contribution of smog forming materials is reduced. This reduction of excess gasoline is achieved by increasing the portion of the work of compression available to evaporate gasoline. To accomplish these results, the carburetor choke on the engine is caused to pass through a cycle of opening and delayed closing, during starting, by the actions of solenoids, spring loaded dashpots, and temperature sensitive elements, acted on by ambient temperatures and current from the battery.

27 Claims, 14 Drawing Figures PATL'IHED 3,732,856

sum 1 OF 7 INVENTOR. JOSEPH C. F l REY BY @FLWF PATEHTEUHAYISIGH I $732,856

SHEET 2 [IF 7 FIG 4 INVENTOR.

JOSEPH o? FIREY PATENTED 51975 3, 732,856

SHEET 3 [1F 7 FIG 5 All PATEEH'L'UMAYISISYS $732,856

m 5 OF 7 FIG 9 FIG- IO INVENTOR. JOSEPH C. Fl REY INVENTOR. JOSEPH C. Fl REY PATENTED 3,732,856

SHEET 7 0F 7 FIG I3 FIG l4 INVENTOR. JOSEPH C. FIR EY 11 GASOLINE ENGINE CHOKE DELAY DEVICES SUMMARY OF THE INVENTION It is an object of this invention to provide means for reducing the amount of excess gasoline passed through a gasoline engine during starting. This object can be achieved by causing the carburetor choke to pass through a cycle of initial opening followed by delayed closing or gradual closing during the cranking of the engine for starting. This choke cycle can be accomplished by the actions of a solenoid choke opener and release connected to a thermostatic opener switch, or a choke release connected to a thermostatic closer switch, or a choke closer dashpot and choke release or a choke closer dashpot actuated by a solenoid. By reducing the amount of excess gasoline passed through a gasoline engine, during the starting of the engine, the contribution of smog forming materials to the atmosphere is reduced. Additionally the net consumption of gasoline by the engine will be reduced and starting will be rendered easier. It is a further object of this inven" tion to accomplish the foregoing desirable objectives by means of relatively inexpensive devices which can readily be adapted to existing gasoline engine carburetors or fuel injection systems. These and other objects of this invention may be accomplished by use of the devices set forth in greater detail in the following descrip tions of the invention and claims.

DETAILED DESCRIPTION OF THE INVENTION Each of the forms of this invention can be used in conjunction with either the typical hand operated choke control or any of the typical automatic choke controls. Since the automatic choke control is the more popular today, the several sketches of this invention show its use in conjunction with one kind of automatic choke control only, without intending to limit the use of this invention to this combination. Many of the automatic choke controls in use today comprise a thermostatic choke control element, responsive to ambient and engine temperature so as to open the choke as ambient and/or engine temperatures increase, and a startup choke opener element, responsive to intake manifold vacuum or starting motor current so as to open the choke somewhat when the engine commences firing during starting. In the attached sketches of this invention, the thermostatic choke control element is labeled A and is usually shown by the symbol of a large circle with an X across it; and the startup choke opener is labeled B and is usually shown by the symbol of a rectangle with an X across it.

Further in the attached sketches of this invention conventional choke plates and choke actuating levers are shown positioned within the air flow passage to the engine carburetor, the opening and closing directions of said choke plates being designated thereon by arrowed arcs marked and C for opening and closing directions respectively.

The several forms of this invention are devices added to the usual automatic choke control or the usual manual choke control and act thereon and upon the choke actuating lever of the choke plate of a gasoline engine carburetor or the mixture enrichening control of a fuel injection system to cause the choke plate or mixture enrichener to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting. Subsequently these devices automatically release the choke plate or other mixture enrichener to close to the extent permitted by the usual automatic or manual choke control, after a delay time interval of engine cranking. The choke plate or other mixture enrichener then becomes operative to enrichen the air fuel mixture in order that the engine may start firing. These devices all contain three components: a choke opener component to automatically open and hold fully open the choke plate or other mixture enrichener at the initiation of the cranking of the engine; a choke releaser component to automatically release the choke or other mixture enrichener from the fully open position and cause the choke or other mixture enrichener to close to the extent permitted by the usual automatic or manual choke control; a delay timer component to automatically set the delay time interval of engine cranking which intervenes between the initiation of the cranking of the engine and the full closure of the choke plate or other mixture enrichener to the extent allowed by the usual automatic or manual choke control. Different kinds of openers, releasers and delay timers can be used and in various differing combinations. A solenoid and magnetic piston, one of which connects to the usual automatic or manual choke control and the other of which connects to the actuating lever of the choke or other mixture enrichener, can be used as a choke opener component. Another kind of opener component consists of a piston and locking bar which engage a hold open ratchet on the choke shaft or mixture enrichener control so that the choke or other mixture enrichener, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after stopping. A releaser component for the solenoid and magnetic piston opener can be a releaser switch which de-energizes the opener solenoid, the releaser switch being opened by a bimetallic thermostat. For locking bar and ratchet openers a solenoid releaser, acting on a magnetic piston, can be used to unlatch the locking bar from the ratchet. Alternatively cranking intake manifold vacuum can be applied via a cylinder to the piston of a locking bar and ratchet opener to accomplish releasing by unlatching the locking bar from the ratchet. A bimetallic thermostat element, heated by battery current during cranking, can be used as a delay timer component by acting, when sufficiently heated, upon switches to de-energize opener solenoids or to energize releaser solenoids. Flow restrictors interposed between the engine intake manifold and a releaser cylinder and piston can function as a delay timer component by delaying the full application of cranking intake manifold vacuum upon the releaser piston. A dashpot, consisting of a cylinder, piston and spring, with air bleed across the piston restricted in the choke closing direction of piston motion, can act upon the choke actuating lever or mixture enrichener control as a delay timer component to regulate how long a time intervenes between release and full closure of the choke or other mixture enrichener.

One preferred from of this invention is shown in FIG. 1 wherein a solenoid choke opener and releaser, 10, is contained in the choke mechanism driving the choke actuating lever, 11, and the choke plate, 12, in the air flow passage, 13, to the engine carburetor. Energizing the solenoid, 14, of the choke opener and releaser, 10, forces the magnetic piston, 15, against the choke closer spring, 16, and holds the choke plate, 12, wide open.

Deenergizing the solenoid, 14, rleases the piston, 15, which is then forced by the choke closer spring, 16, to close the choke fully except as limited by the actions of the thermostatic choke control element, A, and the startup choke opener, B. Hence, with the solenoid, 14, de-energized, the actions of the choke are essentially the same as would be obtained if the solenoid choke opener and release, 10, of this invention, were not present. The solenoid, 14, is energized from the battery via the circuit shown in FIG. 3, containing the following parts: a battery, 3, a typical engine starter switch, 31, a typical engine starter solenoid, 32, to actuate the usual electric starting motor switch, the solenoid, 14, of the solenoid choke opener and release, 10, a thermostatic choke releaser switch, 33, the usual cam actuated ignition points and condenser, 34, of the engine ignition system. The thermostatic choke releaser switch, 33, is shown in'FlG. 2, and consists of an electrically heated bimetallic strip, 21, which moves in the direction h when heated and in the direction when cooled, a contactor switch, 22, which is opened against the spring, 23, when the bimetallic strip, 21, becomes sufficiently deflected in the heated direction, and whose terminals a and b connect into the circuit of the solenoid, 14, as shown in FIG. 3. The bimetallic strip, 21, is electrically heated by battery current passing through the ignition points, 34, the connection point, e, the bimetallic strip 21, the connection point, f, and the engine starter switch, 31, as shown in FIG. 3. The contactor switch, 22, is insulated as necessary from the bimetallic strip, 21, including insulating the actuating bar whereby the bimetallic strip, 21, acts upon the contactor switch, 22, to open said switch. When a cold gasoline engine is tobe started the starter switch, 31, is manually closed, energizing the starter solenoid, 32, and hence the engine starting electric motor, and the choke opener and release solenoid, 14, the thermostatic choke releaser switch, 33, being closed since the bimetallic strip is cold at the beginning. Hence, the choke, 12, is at first automatically held fully open while the engine is cranked by the electric starting motor. As the engine is cranking, a heating electric current is passed through the bimetallic strip, 21, whenever the ignition points, 34, are closed, and the consequent temperature rise causes the bimetallic strip, 21, to move in the direction h. Eventually the bimetallic strip, 21, will open the switch, 22, and de-energize the solenoid, 14, causing the choke, 12, to close as fully as allowed by the thermostatic choke control element, A, and the startup choke opener, B. The engine may then start firing and subsequently warm up fully. When the engine starts firing, the starter switch, 31, is opened and thereafter the starter solenoid, 32, the solenoid, 14, and the bimetallic strip, 21, will no longer have battery current flowing through them. The delay time interval during which the choke, 12, is held fully open by the solenoid choke opener and release, 10, increases as the ambient air temperature decreases since the bimetallic strip, 21, starts initially further deflected in the direction 0. The desired delay time interval characteristics of the thermostatic releaser switch, 33, can be adapted to the requirements of any particular gasoline engine by a proper selection of the kind and geometry of the metals in the bimetallic strip, 21, the gap between the bimetallic strip and the button of the contactor switch, 22, and the stiffness of the hold closed spring, 23, of the contactor switch. In some cases it may be desirable to interpose a current reducing resistor in series with the bimetallic strip in order to modify the delay time interval characteristics of the thermostatic releaser switch. The delay time interval characteristics can also be further modified by connecting terminal e of the bimetallic strip, 21, to point 3 of FIG. 3, in which case battery current will flow continuously instead of intermittently, through the bimetallic strip, 21, whenever the starter switch, 31, is closed.

Another form of this invention is shown in FIG. 4 wherein a solenoid choke releaser, 40, engages a locking bar into a single or multiple step hold open ratchet, 41, on the choke actuating lever, 42, connected to the choke plate, 43, in the air flow passage, 44, to the engine carburetor. Energizing the solenoid, 45, of the solenoid choke releaser, 40, forces the locking bar, 46, against the ratchet engaging spring and disengages it from the hold open ratchet, 41, and the choke, 43, is then free to close as fully as allowed by the thermostatic choke control element, A, and the startup choke opener, B. The solenoid, 45, is energized from the battery via the circuit shown in FIG. 6, containing the following parts: a battery, 60, an engine starter switch, 61, an engine starter solenoid, 62, to actuate the electric starting motor switch, the solenoid, 45, of the solenoid choke releaser, 40, a thermostatic closer switch, 63, the usual cam actuated ignition points and condenser, 64, of the engine ignition system. The thermostatic closer switch, 63, is shown in FIG. 5, and consists of an electrically heated bimetallic strip, 51, which moves in the direction h when heated and in the direction c when cooled, a contactor switch, 52, which is closed against the spring, 53, when the bimetallic strip, 51, becomes sufficiently deflected in the heated direction and whose terminals a and b connect into the circuit of the solenoid, 45, as shown in FIG. 6. The design, construction, and operation of the thermostatic closer switch, 63, are essentially the same as for the thermostatic releaser switch, 33, previously described, except that the closer switch, 63, closes the circuit to energize the solenoid, 45, after a delay time interval whereas the releaser switch, 33, opens the circuit to de-energize the solenoid, 14, after a delay time interval. When the engine is firing and warmed up, the choke, 43, is held wide open by action of the automatic choke thermostatic element, A, and the locking bar, 46, is engaged with the hold open ratchet, 41, to hold the choke wide open, the solenoid, 45, being de-energized and the thermostatic closer switch, 63, being reopened by cooling of the bimetallic strip, 51, since the starter switch, 61, is open. After the engine is stopped and cools down to ambient temperature, the choke, 43, remains locked open from the foregoing effects of the last preceding period of warm operation of the engine. When the cold engine is to be started again, the starter switch, 61 is manually closed, energizing the starter solenoid, 62, and hence the engine starting electric motor, but the solenoid, 45, of the choke releaser, 40, is not at first energized since the thermostatic closer switch, 63, is open. Thus the choke, 43, is automatically held open until the bimetallic strip, 51, of the thermostatic closer switch, 63, is sufficiently heated by battery current to close the switch, 52, and energize the solenoid, 45, to release the locking bar, 46, from the ratchet, 41, thus releasing the choke, 43, to close as fully as allowed by the thermostatic choke control element, A, and the startup choke opener, B. The delay time interval, during which the choke is held open for the FIG. 4 form of this invention is seen to vary with ambient temperature in the same manner as previously described for the FIG. 1 form of this invention.

Another form of this invention is shown in FIG. 7 wherein a solenoid actuated choke closer dashpot, 70, is contained in the choke mechanism driving the choke actuating lever, 71, and the choke plate, 72, in the air flow passage, 73, to the engine carburetor. Energizing the solenoid, 74, of the choke closer dashpot, '70, forces the magnetic piston, 75, against the choke closer spring, 76, and moves the choke plate, 72, to wide open. As the choke plate, 72, reaches the wide open position, the collar, 77, engages the button of the solenoid release switch, 78, which is opened thereby, causing the solenoid, 74, to be de-energized. The solenoid, 74, is energized from the battery via the circuit shown in FIG. 8, containing the following parts: a battery, 80, an engine starter switch, 81, an engine starter solenoid, 82, to actuate the electric starting motor switch, the so lenoid, 74, of the solenoid actuated choke closer dashpot, 70, and the solenoid release switch, 78, consisting of the magnetic switch bar, 83, a hole closed spring, 84, and a hold open solenoid, 85. When a cold gasoline engine is to be started, the starter switch, 81, is manually closed, energizing the starter solenoid, 82, and hence the engine starting electric motor, and the solenoid, 74, of the solenoid actuated choke closer dashpot, 70, and the hold open solenoid, 85, of the solenoid release switch, 78. The choke plate, 72, is thus automatically forced wide open, at which time the collar, 77, pushes the magnetic switch bar, 83, against the hold open solenoid, 85, which will then hold the solenoid release switch, 78, open against the hold closed spring, 84, and hence de-energize the solenoid, 74. The choke closer spring, 76, forces the piston, 75, in the choke closing direction causing the check valve, 79, to close, after which the rate at which the piston, 75, closes the choke is determined by the rate at which the air trapped in the chamber, 701, can escape through the restricted flow passage, 702. As a result of these actions, the choke, 72, closes rather gradually to the maximum extent allowed by the thermostatic choke control element, A, and the startup choke opener, B. After the engine commences firing and running the starter switch, 91, is opened, thus de-energizing the starter solenoid, $2, and the hold open solenoid, 85, as a result of which the release switch, 78, is again closed by the hold closed spring, 84. The net effect of the FIG. 7 form of this invention is to fully open the choke at the moment of starting and then to gradually close the choke as the engine is being cranked. The rate of this gradual closing can be adapted to the starting requirements of a particular gasoline engine by suitable selection of the diameter of the piston, 75, the stiffness of the spring, 76, and the size and length of the restricted flow passage, 702. The restricted flow passage may be a separate passage through the piston as shown in FIG. 7 or may be a passage through the check valve or may be the clearance between the piston and the cylinder.

Another form of this invention is shown in FIG. 9 wherein a choke closer dashpot, 90, is contained in the choke mechanism driving the choke actuating lever, 91, and the choke plate, 92, in theair flow passage, 93, to the engine carburetor. A solenoid choke releaser, 94, engages a locking bar into a single or multiple step hold open ratchet, 95, on the choke actuating lever, 91.

Energizing the solenoid, 96, of the solenoid choke releaser, 94, disengages the locking bar, 97, from the ratchet, 95, and the choke, 92, is then moved in the closing direction by the spring, 98, acting on the piston, 99, of the choke closer dashpot, 90. Movement of the piston, 99, closes the check valve, 901, after which the rate at which the piston, 99, closes the choke is determined by the rate at which the air trapped in the chamher, 902, can escape through the restricted passage, 903. As a result of these actions, the choke, 92, is automatically wide open at the moment of engine starting and thereafter closes rather gradually to the maximum extent allowed by the thermostatic choke control element, A, and the startup choke opener, B. The rate of the gradual choke closing can be adapted to the starting requirements of a particular gasoline engine by suitable selection of the diameter of the piston, 99, the stiffness of the spring, 98, and the size and length of the air restriction passage, 903. The restricted flow passage may be a separate passage through the piston as shown in FIG. 9 or may be a passage through the check valve or may be the clearance between the piston and the cylinder. The solenoid, 96, is energized from the battery via the circuit shown in FIG. 10, containing a battery, 100, an engine starter switch, 101, an engine starter solenoid, 102, to actuate the electric starting motor switch, and the solenoid, 96, of the solenoid choke release, 94. When the engine is firing and warmed up, the choke, 92, is held wide open by action of the automatic choke thermostatic element, A, and the locking bar, 97, is engaged with the hold open ratchet, 95, to hold the choke wide open, the solenoid, 96, being deenergized since the starter switch, 101, is open. After the engine is stopped and cools down to ambient temperatures, the choke, 92, remains locked open from the foregoing effects of the last preceding period of warm operation of the engine. When the cold engine is to be started again, the starter switch, 101, is manually closed, energizing the starter solenoid, 102, and hence the engine electric starting motor, the solenoid, 96, thus releasing the locking bar, 97, from the ratchet, 95. The choke is then free to close as fast as the choke closer dashpot, 90, will allow and to the maximum extent allowed by the thermostatic choke control element, A, and the startup choke opener, B.

The vacuum choke release shown in FIG. 11 can be substituted for the solenoid choke releaser, 94, of the FIG. 9 form of this invention, or the solenoid choke releaser, 40, of the FIG. 4 form of this invention. When the engine is being cranked by the electric starting motor, an engine intake manifold cranking vacuum of about 3 to 5 inches of mercury is obtained at closed throttle. The area of the piston, H01, and the strength and preset of the spring, 111, are selected so that this amount of vacuum, applied from the intake manifold via the connection, 112, with the connection, 115,

closed off, is sufficient to disengage the locking bar, 97, from the hold open ratchet, 95. Hence the action of the vacuum choke release is similar to that of the solenoid choke releaser except that release is delayed until an adequate intake manifold vacuum is reached by engine cranking and this vacuum is applied to the piston, ll 10. The delay in releasing the choke can be increased by making the flow restriction, I13, smaller or longer or by increasing the active volume, 1l 6, of the cylinder, 1 1 .4.

When the engine is firing and warmed up the choke is held wide open by action of the automatic choke thermostatic element, A. If the engine is then stopped,

' the locking bar, 97, will re-engage the ratchet, 95, to

A firing and fully warmed up engine will frequentlyoperate over a wide range of power settings and hence of intake manifold vacuums. In consequence the piston and spring of the vacuum choke release of FIG. 11 will be moved back and forth as the intake manifold vacuum changes. To reduce the duration of this back and forth motion and hence to prolong the useful life of the vacuum choke release of FIG. 1 1, an independent connection, 115, can be provided from the active volume, 116, of the cylinder, 114, to the outlet, 120, of the viscous vacuum breaker sketched in FIG. 12. The viscous vacuum breaker of FIG. 12 consists of a capillary tube,

121, vented to the atmosphere at 124, a chamber, 122,

partially filled with a viscous fluid, 123, and an outlet connection, 120. The viscous vacuum breaker chamber, 122, can be mounted within the engine jacket water system, or in contact with the engine jacket water system, or within the exhaust heated stove section of the engine intake manifold, or in contact with the stove section of the engine intake manifold. When cold, the viscosity of the fluid, 123, is sufficient that it will not flow out of the capillary tube, 121, within the normal time of engine startup. Hence when cold starting an engine the cranking intake manifold vacuum can come to be applied fully to the piston, 110, of the vacuum choke release and the locking bar, 97, can be disengaged from the ratchet, 95. On the other hand, when the engine is fully warmed up the viscosity of the fluid, 123, is sufficiently reduced that it readily flows out of the capillary tube, 121, and thus prevents application of sufficient vacuum to the piston, 110, to move it against the spring. As a result, the choke is released to close when the engine is cold, but the releasing action does not occur when the engine is warmed up.

The thermostatic vacuum breaker sketched in FIG. 13 can be used in lieu of the viscous vacuum breaker of FIG. 12. The'thermostatic vacuum breaker consists of a valve, 130, pisitioned by a bimetallic strip, 131, said valve opening a vacuum breaker passage via the independent connection, 132, to the active cylinder volume, 1 16, of the cylinder, 114, of the vacuum choke release. The bimetallic strip, 131, tends to move in the direction 0 when cooled and in the direction h when heated. The thermostatic vacuum breaker is mounted on a portion of the engine whose temperature rises appreciably when the engine warms up, such as the intake manifold stove or the cylinder head. When the engine is cold the vacuum breaker valve, 130, is held closed by the bimetallic strip, 131, and the cranking intake manifold vacuum can come to be applied fully to the piston, 110, of the vacuum choke release, thus leading to release of the choke. When the engine is warmed up, the valve, 130, is open and sufficient vacuum can no longer be applied to the piston, 1 10, to move it against the preset of the spring, 111.

In addition to the essentially linear motion of the choke actuating devices described in FIGS. 1, 4, 7, and 9, a rotational method of actuating the choke shaft can also be used, an example of which is shown in FIG. 14.

A thermostatic choke control element, A, a startup choke opener, B, and a solenoid choke opener and release, 140, similar to item 10 of FIG. 1, are mounted on a free alignment shaft, 141, and connected so as to add their individual motions rotationally to the choke shaft, 142. v

The piston, spring and cylinder elements, shown for example as items and of FIGS. 7 and 9 respectively are intended to include the mechanical compo nents and configuration as sketched and also the equiv alent elements made up of metallic bellows and springs or alternatively made up of clamped flexible diaphragms in chambers with springs, all such configurations being referred to in the description and in the claims of this invention as piston, cylinder and spring elements.

The various electric circuits shown as examples in FIGS. 3, 6, 8, and 10 contain a single pole, single throw starter switch and associated starter solenoid wiring but it is not intended to limit the use of this invention to this starter switch arrangement.

Most gasoline engines today use a carburetor to meter the gasoline to the engine and a choke plate is added at the inlet to the carburetor, and is positioned via the choke actuating lever attached thereto, to act as a starting mixture enrichener to enrichen the air-fuel mixture going to the engine by supplying excess gasoline in order that the engine may start firing when cold. Some gasoline engines use fuel injection systems to meter the gasoline to the engine. Several different types of fuel injection systems are used, each equipped with a starting mixture enrichener, the equivalent of a choke, to supply the excess gasoline needed to enrichen the mixture for cold starting. The terms choke and choke plate are used in the description and claims of this invention to mean any starting mixture enrichener as used on an engine gasoline metering device. The term carburetor is used in the description and claims of this invention to mean any engine gasoline metering device. The term choke open is used in the description and claims of this invention to mean the choke is inoperative and is not supplying excess gasoline to the engine. The term choke closed is used in the description and claims of this invention to mean the choke is operative and is supplying excess gasoline to the engine.

When a gasoline engine is to be started cold, gasoline, considerably in excess of that needed to create a spark ignitable airfuel vapor mixture, is mixed with the incoming air in the carburetor because only a small portion of the liquid gasoline evaporates when the engine is cold, and it is only the evaporated gasoline portions which mix with the air to form the ignitable airfuel vapor mixture. When a gasoline engine is running fully warmed up, all of the gasoline mixed with the incoming air by the carburetor is evaporated and the airfuel vapor mixture, metered by the unchoked carburetor, is such that sufficient oxygen is available to burn all of this gasoline. Hence, for the excess gasoline supplied to the engine by choking during cold starting, there is no oxygen available to burn it, and this excess gasoline is eventually discharged to the atmosphere as unburned hydrocarbon material. Unbumed hydrocarbon materials are well known as a contributor to atmospheric smog and, thus, each time a gasoline engine is started cold, an undesirable contribution is made to atmospheric smog materials. It is a purpose of this invention to reduce this gasoline engine, cold starting contribution to atmospheric smog by reducing the quantity of excess gasoline metered to the engine during cold starting.

To evaporate liquid gasoline requires that heat be transferred to the gasoline at least equal to the latent heat of evaporation of those portions evaporating. In a cold engine, which is not firing, the only sources of heat energy are the metal of the carburetor, manifolds, valves, cylinders, and pistons of the engine, the incoming air, the unevaporated gasoline portions, and a portion of the engine cranking work. Usually it is only at quite high ambient temperatures that a gasoline engine commences firing on the first revolution of starting. A cold engine turns over several revolutions before firing, the number of such cranking revolutions generally increasing as the engine is colder. During the non-firing cranking revolutions the electric starter motor overcomes engine friction forces and compresses and expands the air-fuel vapor mixture. The work of com pressing the air-fuel vapor mixture increases its temperature above the valve prevailing in the engine intake manifold, the maximum rise in temperature occurring when maximum compression pressure is attained. Thereafter during expansion the temperature of the airfuel vapor mixture decreases from this maximum attained value and would again reach the value prevailing in the engine intake manifold if no liquid gasoline evaporation occurred and if no heat transfer took place between the air-fuel vapor mixture and the adjacent, colder engine parts (piston, cylinder, valves, etc.). Hence, in general, the air-fuel vapor mixture is hotter than the adjacent engine parts throughout most of the compression and expansion processes and, in consequence, heat energy is transferred from this hotter airfuel vapor mixture to the adjacent colder piston, cylinder wall, cylinder head, valves, etc. causing an increase in the temperature of these engine parts. That portion of the cranking work of the electric starter motor devoted to overcoming the friction force between the cylinder wall and the piston and rings reappears as increased energy content and hence increased temperature of these engine parts. The actual temperature rise .of these engine parts increases as the cranking work increases, but decreases as more gasoline is evaporated from these surfaces since latent heat of gasoline evaporation is transferred from these surfaces into the evaporating gasoline portions. It is thus seen that one of the better ways to start a cold gasoline engine is to crank the engine, without excess gasoline admission, until a sufficiently high temperature is reached that, when excess gasoline is admitted, enough evaporates to create an ignitable air-fuel vapor mixture and in consequence the engine commences firing immediately upon the admission of excess gasoline. in this way the amount of excess gasoline needed for cold starting can be reduced. It is an object of this invention to automatically accomplish this improved manner of cold starting gasoline engines.

The engine choke acts to supply the excess gasoline needed for cold starting by restricting incoming air flow upstream of the carburetor and in this way increasing the pressure difference between the carburetor float bowl and the air flowing through the venturi and in consequence a greater quantity of gasoline flows through the carburetor jets into the incoming air. The amount of excess gasoline thus metered into the air incally holding the choke wide open, and hence inoperative, during the early period of cranking and then only allowing the choke to close after the cranking work has sufficiently increased the temperatures of various interior engine surfaces that the excess gasoline, admitted upon choke closure, is adequately evaporated to produce an ignitable air-fuel vapor mixture immediately or shortly after closing the choke. In this way less excess gasoline is needed to start a cold gasoline engine than is needed with present-day automatic chokes which automatically hold the choke closed from the very commencement of cranking. When the choke is held closed from the commencement of cranking the excess gasoline supplied during the first pair of cranking revolutions suppresses temperature rise of the interior engine surfaces by removing heat from these surfaces to supply the latent heat of evaporation of those excess gasoline portions which evaporate. If the engine does not fire during these first two cranking revolutions, as is normally the case for a cold start, the excess gasoline evaporated is of no subsequent benefit since it is discarded into the engine exhaust manifold before the next active cranking revolutions commence. The suppression of temperature rise of the interior engine surfaces caused by choke closure during the first pair of cranking revolutions, as described above, takes place also during the second and all subsequent pairs of cranking revolutions, for which the choke is held closed, until the engine commences firing and starts. As a result the interior engine surfaces warm up only slowly during cranking with the choke closed and a longer cranking duration is needed to bring the temperature of these interior engine surfaces up sufficiently that the ignitable air-fuel vapor mixture needed for firing and starting is achieved, than is the case if the choke is open. Hence the present-day automatic chokes require greater quantities of excess gasoline during cold starting than would be required if the devices of this invention were used, in part because the cranking period to start is longer and in part because excess gasoline is needlessly and detrimentally admitted throughout this cranking period.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A device to hold open and inoperative, the choke, or other starting mixture enrichener, of a gasoline engine, at the initiation of starting, and to subsequently release the choke, or other mixture enrichener, to close and become operative, after a time interval, comprising a choke or enrichener opener component, a choke or enrichener releaser and closer component, and a delay timer component.

2. A device to hold open and inoperative the choke, or other starting mixture enrichener, of a gasoline engine, at the initiation of starting, and to subsequently release the choke, or other mixture enrichener, to close and become operative, after a time interval comprising a choke or enrichener opener component, a choke or enrichener releaser and closer component, and a delay time component; said opener component being solenoid actuated, using battery current via the engine starting switch, or latch and ratchet actuated from the preceding warmed-up period of engine operation; said releaser component being a switch, for solenoid actuated openers, or a battery powered solenoid, or a spring loaded intake vacuum actuated dashpot, for latch and ratchet actuated openers; said delay timer component being a bimetallic thermostat heated by battery current via the engine starter switch and the engine ignition points or via the engine starter switch only, to actuate releaser switches or releaser solenoids, or a spring loaded dashpot with check valve and air bleed, or a restrictor passage with or without a vacuum breaker to regulate application of intake vacuum to a dashpot releaser.

3. A device as described in claim 1 wherein; the choke or enrichener opener component is a solenoid and spring loaded magnetic piston which opens the choke when the solenoid is energized and whose spring acts to close the choke when the solenoid is deenergized, said solenoid being energized by battery current supplied via the engine starting switch and a thermostatic opener switch; the choke or enrichener releaser component is the thermostatic opener switch, held closed by a spring; the delay timer component is a bimetallic strip, heated by battery current via the engine starter switch and the engine ignition points in series, which acts to open the thermostatic opener switch when sufficiently heated.

4. A device as described in claim 3 wherein the bimetallic strip of the delay timer component is heated by battery current via the engine starter switch only.

5. A device as described in claim 1, wherein; the choke or enrichener opener component is a hold open ratchet on the choke or enrichener shaft or other actuating piece, engageable with a latch; the choke or enrichener releaser component is a solenoid acting when energized, to disengage the latch, against the latch spring, from the ratchet, energized by battery current supplied via the engine starting switch and a thermostatic closer switch held open by a spring; the delay timer component is a bimetallic strip, heated by battery current via the engine starter switch and the engine ignition points in series, which ,acts to close the thermostatic closer switch when sufficiently heated.

6. A device as described in claim 5 wherein the bimetallic strip of the delay timer component is heated by battery current via the engine starter switch only.

7. A device as described in claim 1, wherein; the choke or enrichener opening component is a solenoid with spring loaded magnetic piston or diaphragm which opens the choke when the solenoid is energized and whose spring acts to close the choke when the solenoid is deenergized, said solenoid being energized by battery current supplied via the engine starting switch and a release switch, held closed by a spring or held open by another solenoid when the latter is energized by battery current supplied via the engine starting switch; the choke or enrichener releaser component is a collar on the piston rod of the magnetic piston or diaphragm which opens the release switch when the choke reaches wide open position; the delay timer component is a check valve and separate air bleed restriction in the magnetic piston or diaphragm or its sealed cylinder end, acting to slow the spring actuated closure of the choke or enrichener.

8. A device as described in claim 1, wherein; the choke or enrichener opener component is a hold open ratchet on the choke or enrichener shaft or other actuating part, engageable with a latch; the choke or enrichener releaser component is a solenoid acting, when energized, to disengage the latch, against the latch spring, from the ratchet, energized by battery current supplied via the engine starting switch; the delay timer component is a check valve and separate air bleed restriction in a spring loaded diaphragm, bellows, or piston, or its sealed cylinder end, on the choke actuating link, acting to slow the spring actuated motion of the piston, diaphragm, or bellows, to close the choke or enrichener.

9. A device as described in claim 1, wherein; the choke or enrichener opener component is a hold open ratchet on the choke or enrichener shaft or other actuating part, engageable with a latch; the choke or enrichener releaser component is a dashpot, spring loaded to engage the latch, actuated by an intake manifold vacuum of two to four inches of mercury to disengage the latch from the ratchet, said dashpot consisting of a piston in a cylinder or a sealed diaphragm within a chamber, or a metallic bellows, the sealed volume on the vacuum side of which is connected, via a restrictor passage, to the engine intake manifold, and separately to a vacuum breaker; the delay timer component is the restrictor passage in the intake manifold connection, proportioned to the sealed cylinder or chamber volume on the vacuum side of the releaser dashpot to achieve the desired timer delay.

10. A device as described in claim 9 wherein the vacuum breaker in the releaser component is a valve, positioned by a bimetallic strip so that the valve is closed when the bimetallic strip is cold and the valve is open when the bimetallic strip is warm, the bimetallic strip being heated by being in contact with a portion of the engine whose temperature increases as the engine warms up, such as the engine jacket, the carburetor, stove, etc.

11. A device as described in claim 9 wherein the vacuum breaker in the releaser component is a capillary tube, the upper end of which is open to the atmosphere and the lower end of which is submerged into a volume of viscous liquid contained in a sealed chamber whose free space, above the viscous liquid, connects separately to the sealed cylinder or chamber volume on the vacuum side of the releaser dashpot, said chamber and viscous liquid being in contact with a portion of the engine whose temperature increases as the engine warms up, such as the engine jacket, the carburetor stove, etc.

12. A device as described in claim 9 wherein an additional time delay device is mounted on the choke or enrichener actuating link consisting of a check valve and separate air bleed restriction in a spring loaded diaphragm, bellows, or piston, or its sealed cylinder end, acting to slow the spring actuated motion of the piston, diaphragm, or bellows to close the choke or enrichener.

13. A device as described in claim 5 wherein an additional time delay device is mounted on the choke or enrichener actuating link consisting of a check valve and separate air bleed restriction in a spring loaded diaphragm, bellows, or piston, or its sealed cylinder end, acting to slow the spring actuated motion of the piston, diaphragm, or bellows to close the choke or enrichener.

14. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be held fully open and inoperative at the initiation of the cranking of the engine for starting and which then releases said choke plate to close to the extent permitted by the usual automatic or manual choke control, after a delay time interval of engine cranking, the choke plate then becoming operative to enrichen the air fuel mixture in order that the engine may start firing, said device comprising the following listed components:

a. A choke opener component to automatically open and hold fully open the choke plate at the initiation of the cranking of the engine.

b. A choke releaser component to automatically release the choke from the fully open position and cause the choke to close the the extent permitted by the usual automatic or manual choke control.

c. A delay timer component to automatically set the delay time interval of engine cranking which intervenes between the initiation of 'the cranking of the engine and the full closure of the choke plate to the extent allowed by the usual automatic or manual choke control.

15. A device, added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently, after a delay time interval of engine cranking, releases said choke plate which then closes, to the extent permitted by the usual automatic or manual choke control, and becomes operative to enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components:

a. A choke opener component to automatically open fully the choke plate at the initiation of the cranking of the engine, the opening being accomplished by a solenoid and magnetic piston, one of which connects to the choke actuating lever and the other of which connects to the usual automatic or manual choke control, the solenoid of which is energized with battery current via the engine starting switch and a choke releaser switch in series therewith, such solenoid energizing causing the magnetic piston to move, against a choke closer spring, to open the choke fully.

b. A choke releaser and closer component to automatically release and close the choke, after a delay time interval of engine cranking, the releasing being accomplished by the aforementioned releaser switch in series with the solenoid of the choke opener component so that opening the switch de-energizes said solenoid, the closing being accomplished by the aforementioned choke closer spring acting on the magnetic piston of the choke opener component in a direction to close the choke, said spring being strong enough to close the choke, to the extent allowed by the usual automatic choke control or the usual manual choke control, but being weak enough to be overcome by the force of the aforementioned solenoid acting on the aforementioned magnetic piston.

c. A delay timer component to automatically set the delay time interval of engine cranking with the choke fully open so that said time interval increases as ambient air temperature decreases, said delay timer component being a bimetallic thermostat element heated by battery current via the engine starter switch, said bimetallic thermostat element being so positioned that it mechanically opens the choke releaser switch of the aforementioned choke releaser and closer component after being sufficiently heated by said battery current and is thus sufficiently deflected as to open said switch, the required time of heating to switch opening, and thus the delay time interval being longer as the ambient temperature and thus the beginning temperature of the bimetallic thermostat element becomes lower.

16. A device added to the usual'automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently, after a delay time interval of engine cranking, releases said choke plate which then closes, to the extent permitted by the usual automatic or manual choke control, and becomes operative to enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components:

a. A choke opener component to automatically hold fully open the choke plate at the initiation of the cranking of the engine, the holding being accomplished by a magnetic piston and locking bar, spring engaged to a hold open ratchet on the choke shaft so that the choke plate, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after being stopped.

b. A choke releaser component to automatically release the choke, after a delay time interval of engine cranking, the releasing being accomplished by energizing a solenoid which is strong enough to move the aforementioned magnetic piston of the choke opener component against the ratchet engaging spring and so disengage the locking bar from the hold open ratchet and thus release the choke plate to close to the extent allowed by the usual automatic choke control or the usual manual choke control, said solenoid being energized from the battery via the engine starter switch and a thermostatic closer switch in series therewith.

c. A delay timer component to automatically set the delay time interval of engine cranking with the choke fully open so that said time interval increases as ambient air temperature decreases, said delay timer component being a bimetallic thermostat element heated by battery current via the engine starter switch, said bimetallic thermostat element being so positioned that it mechanically closes the aforementioned thermostatic closer switch of the aforementioned choke releaser component after being sufficiently heated by said battery current and is thus sufficiently deflected as to close said switch, the required time of heating to switch closure, and thus the delay time interval, being longer as the ambient temperature and thus the beginning temperature of the bimetallic thermostat element becomes lower.

17. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently, after a delay time interval of engine cranking, releases said choke plate which then closes, to the extent permitted by the usual automatic or manual choke control, and becomes operative to enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components:

a. A choke opener component to automatically hold fully open the choke plate at the initiation of the cranking of the engine, the holding being accomplished by a piston and locking bar, spring engaged to a hold open ratchet on the choke shaft so that the choke plate, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after being stopped.

b. A choke releaser component to automatically re lease the choke, after a delay time interval of engine cranking, the releasing being accomplished by applying intake manifold craning vacuum via a restricted tube to the closed end of a cylinder, fitted closely around the aforementioned piston of the choke opener component, said closed end being on the piston side opposite the locking bar, in order to move the piston and locking bar against the engaging spring in a direction to disengage the locking bar from the aforementioned hold open ratchet and thus release the choke plate to close to the extent allowed by the usual automatic choke control or the usual manual choke control. The piston area of the cylinder is proportioned so that cranking intake manifold vacuum exerts sufficient net force on the piston to fully overcome the opposite acting force of the engaging spring.

c. A delay timer component to automatically set the delay time interval of the engine cranking with the choke fully open, said delay timer component being the restricted tube connecting the closed end of the aforementioned cylinder of the choke releaser component to the engine intake manifold. This restricted tube delays the time of full application of cranking intake manifold vacuum to the piston of the choke opener component until the excess air inside the closed end of the cylinder has flowed through the restricted tube into the intake manifold. The delay time interval of engine cranking can thus be set to the desired value by adjusting the air volume in the closed end of the cylinder and the size of the restriction in the restricted tube, said delay time interval being increased by increasing the air volume and by decreasing the size of the restriction. I

18. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently releases said choke plate which then closes slowly, to the extent permitted by the usual 6 automatic or manual choke control, and becomes operative to gradually enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components:

a. A choke opener component to automatically open fully the choke plate at the initiation of the cranking of the engine, the opening being accomplished by a solenoid with a cylindrical core cavity and a magnetic piston fitted closely to the interior of said cylindrical core cavity one of which connects to the choke actuating lever and the other of which connects to the usual automatic or manual choke control, the solenoid of which is energized with battery current via the engine starter switch and a solenoid release switch in series therewith, such solenoid energizing causing the magnetic piston to move within the cylindrical core cavity of the solenoid, against a choke closer spring, to open the choke plate fully.

b. A choke releaser component to automatically release the choke, the releasing being accomplished by a member, integral with the connection between the choke opener component and the choke actuating lever, which mechanically moves the magnetic switch bar of the aforementioned solenoid release switch against the hold closed spring of the switch and into magnetic contact with a hold open solenoid, said hold open solenoid being energized with battery current via the engine starter switch and having sufficient magnetic field strength, when energized, to hold the magnetic switchbar in magnetic contact with itself against the contrary force of the hold closed spring, said movement of the magnetic switch bar causing the solenoid release switch to open and de-energize the solenoid of the choke opener component, and thus release the choke plate to close slowly to the extent allowed by the usual automatic choke control or the usual manual choke control.

c. A delay timer component to automatically set the rate of closing of the choke plate after it has been released by the choke releaser component comprising; the aforementioned choke closer spring, acting between the cylindrical core cavity of the solenoid and the magnetic piston of the choke opener component in a direction to close the choke plate; the aforementioned magnetic piston fitted with a restricted passage between the faces of the piston and an open passage between these piston faces containing a check valve which closes said open passage whenever the magnetic piston is moved by the choke closer spring in the choke closing direction; the aforementioned cylindri-ca'l core cavity, whose end, toward which the piston moves when opening the choke is atmospherically vented and whose opposite end is closed such that air is trapped in this closed end of the cylindrical core cavity by the closing of the check valve in the open passage of the magnetic piston. This trapped air can only escape via the restricted passage in the magnetic piston, the rate of such escape of trapped air, and hence the rate of closing of the choke being determined by the diameter of the magnetic piston, the strength of the choke closer spring and the size of the restricted flow passage.

19. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently releases said choke plate which then closes slowly, to the extent permitted by the usual automatic or manual choke control, and becomes operative to gradually enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components:

a. A- choke opener component to automatically hold fully open the choke plate at the initiation of the crank-ing of the engine, the holding being accomplished by a magnetic piston and locking bar, spring engaged to a hold open ratchet on the choke shaft so that the choke plate, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after being stopped.

b. A choke releaser component to automatically release the choke, the releasing being accomplished by energizing a solenoid which is strong enough to move the aforementioned magnetic piston of the choke opener component against the ratchet engaging spring and so disengage the locking bar from the hold open ratchet and thus release the choke plate to close slowly to the extent allowed by the usual automatic choke control or the usual manual choke control, said solenoid being energized from the battery via the engine starter switch.

c. A delay timer component to automatically set the rate of closing of the choke plate after it has been released by the choke releaser component comprising a choke closer dashpot element interposed between the choke actuating lever and the usual automatic or manual choke control. This dashpot contains a choke closer spring acting between a hollow cylinder and a piston fitted closely to the interior of said cylinder in a direction to close the choke. The cylinder of said dashpot is atmospherically vented at the end toward which the piston moves when opening the choke and is closed off at the opposite end. The cylinder and the piston of said dashpot connect to the choke actuating lever and the usual automatic or manual choke control in any order desired. The choke closer dashpot piston contains a restricted flow passage and an open flow passage between the piston faces, the open flow passage being fitted with a check valve which closes when the choke closer spring moves the piston toward the closed end of the cylinder. The air thus trapped in the closed end of the cylinder escapes slowly via the restricted flow passage and thus the piston and the choke plate move slowly in the choke closing direction. The rate of such choke closure can be predetermined by proper selection of the piston diameter, the strength of the choke closer spring and the size of the restricted flow passage. A slower rate of choke closure can be obtained by increasing the piston diameter, by reducing the strength of the choke closer spring and by reducing the size of the restricted flow passage.

20. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently releases said choke plate which then closes slowly to the extent permitted by the usual automatic or manual choke control, and becomes operative to gradually enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components:

a. A choke opener component to automatically hold fully open the choke plate at the initiation of the cranking of the engine, the holding being accomplished by a piston and locking bar, spring engaged to a hold open ratchet on the choke shaft so that the choke plate, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after being stopped.

b. A choke releaser component to automatically release the choke, aftera delay time interval of engine cranking, the releasing being accomplished by applying intake manifold cranking vacuum via a restricted tube to the closed end of a cylinder, fitted closely around the aforementioned piston of the choke opener component, said closed end being on the piston side opposite the locking bar, in order to move the piston and locking bar against the engaging spring in a direction to disengage the locking bar from the aforementioned hold open ratchet and thus release the choke plate to close to the extent allowed by the usual automatic or manual choke control. The piston area and hence the cross sectional area of the cylinder is proportioned so that cranking intake manifold vacuum exerts sufficient net force on the piston to fully overcome the opposite acting force of the engaging spring.

c. A primary delay timer component to automatically set the delay time interval of engine cranking with the choke fully open, said primary delay timer component being the restricted tube commecting the closed end of the aforementioned cylinder of the choke releaser component to the engine intake manifold. This restricted tube delays the time of full application of cranking intake manifold vacuum to the piston of the choke opener component until the excess air inside the closed end of the cylinder has flowed through the restricted tube into the intake manifold. The primary delay time interval of engine cranking can thus be set to the desired value by adjusting the air volume in the closed end of the cylinder and the size of the restriction in the restricted tube, said primary delay time interval being increased by increasing the air volume and by decreasing the size of the restriction.

d. A secondary delay timer component to automatically set the rate of closing of the choke plate after it has been released by the choker releaser component comprising a choke closer dashpot element interposed between the choke actuating lever and the usual automatic or manual choke control. This dashpot contains a choke closer spring acting between a hollow cylinder, and a piston fitted closely to the interior of said cylinder in a direction to close the choke. The cylinder of said dashpot is atmospherically vented at the end toward which the piston moves when opening the choke and is closed off at the opposite end. The cylinder and the piston of said dashpot connect to the choke actuating lever and the usual automatic or manual choke control in any order desired. The choke closer dashpot piston contains an open flow passage between the piston faces which is closed by a check valve when the choke closer spring moves the piston toward the closed end of the cylinder. The air thus strapped in the closed end of the cylinder escapes slowly via a restricted flow passage and thus the piston and the choke plate move slowly in the choke closing direction. The rate of such choke closure can be predetermined by proper selection of the piston diameter, the strength of the choke closer spring and the size of the restricted flow passage. A slower rate of choke closure can be obtained by increasing the piston diameter, by reducing the strength of the choke closer spring and by reducing the size of the restricted flow passage. 21. A device as described in claim wherein the heater connections for the heating of the bimetallic thermostat element of the delay-timer component by battery current are made via the engine starter switch and the usual engine ignition points in series therewith. 22. A device as described in claim 16 wherein the heater connections for the heating of the bimetallic thermostat element of the delay timer component by battery current are made via the engine starter switch and the usual engine ignition points in series therewith. 23. A device as described in claim 17 wherein the closed end air volume in the cylinder of the choke'releaser component is provided with another connection to a viscous vacuum breaker in order to prevent needless wear of the choke releaser component during warm operation of the engine. The viscous vacuum breaker consists of a chamber partially filled with a viscous fluid the chamber having an atmospherically vented capillary tube therein which extends deeply into the viscous fluid. The chamber space above the viscous fluid level connects via a tube to the closed end air volume in the cylinder of the choke releaser component. The chamber of the viscous vacuum breaker is mounted in thermal contact with a part of the engine,

such as the jacket water system, whose temperature increases as the engine warms up.

24. A device as described in claim 20 wherein the closed end air volume in the cylinder of the choke releaser component is provided with another connection to a viscous vacuum breaker in order to prevent needless wear of the choke releaser component during warm operation of the engine. The viscous vacuum breaker consists of a chamber partially filled with a viscous fluid the chamber having an atmospherically vented capillary tube therein which extends deeply into the viscous fluid. The chamber space above the viscous fluid level connects via a tubeto the closed end air volume in the cylinder of the choke releaser component. The chamber of the viscous vacuum breaker is mounted in thermal contact with a part of the engine, such as the jacket water system, whose temperature increases as the engine warms up.

25. A device as described in claim 17 wherein the closed end air volume in the cylinder of the choke releaser component is provided with another connection to a thermostatic vacuum breaker in order to prevent needless wear of the choke releaser component during warm operation of the engine. The thermostatic vacuum breaker consists of a valve positioned by a bimetallic thermostat element in the atmospherically vented end of the tube connecting to the closed end air volume in the cylinder of the choke releaser component. The bimetallic thermostat element isarranged to hold the valve closed when cold but to open the valve when sufficiently heated. The bimetallic thermostat element is mounted in thermal contact with a part of the engine, such as the jacket water system, whose temperature increases as the engine warms up.

26. A device as described in claim 20 wherein the closed end air volume in the cylinder of the choke releaser component is provided with another connection to a thermostatic vacuum breaker in order to prevent needless wear of the choke releaser component during warm operation of the engine. The thermostatic vacuum breaker consists of a valve positioned by a bimetallic thermostat element in the atmospherically vented end of the tube connecting to the closed end air volume in the cylinder of the choke releaser component. The bimetallic thermostat element is arranged to hold the valve closed when cold but to open the valve when sufficiently heated. The bimetallic thermostat element is mounted in thermal contact with a part of the engine, such as the jacket water system, whose temperature increases as the engine warms up.

27. A device as described in claim 16 wherein, in addition to the primary delay timer component as described in claim 16, an additional secondary delay timer is incorporated to automatically set the rate of closing of the choke plate after it has been released by the choke releaser component comprising a choke closer-dashpot element interposed between the choke actuating lever and the usual automatic or manual choke control. This dashpot contains a choke closer spring acting between a hollow cylinder and a piston fitted closely to the interior of said cylinder in a direction to close the choke. The cylinder of said dashpot is atmospherically vented at the end toward which the piston moves when opening the choke and is closed off at the opposite end. The cylinder and the piston of said dashpot connect to the choke actuating lever and the usual automatic or manual choke control in any order desired. The choke closer dashpot piston contains an open flow passage between the piston faces which is closed by a check valve when the choke closer spring moves the piston toward the closed end of the cylinder.

The air thus trapped in the closed end of the cylinder escapes slowly via a restricted flow passage and thus the piston and the chock plate move slowly in the choke closing direction. The rate of such choke closure can be predetermined by proper selection of the piston diameter, the strength of the choke closer spring and the size of the restricted flow passage. A slower rate of choke closure can be obtained by increasing the piston diameter, by reducing the strength of the choke closer spring and by reducing the size of the restricted flow passage. 

1. A device to hold open and inoperative, the choke, or other starting mixture enrichener, of a gasoline engine, at the initiation of starting, and to subsequently release the choke, or other mixture enrichener, to close and become operative, after a time interval, comprising a choke or enrichener opener component, a choke or enrichener releaser and closer component, and a delay timer component.
 2. A device to hold open and inoperative the choke, or other starting mixture enrichener, of a gasoline engine, at the initiation of starting, and to subsequently release the choke, or other mixture enrichener, to close and become operative, after a time interval comprising a choke or enrichener opener component, a choke or enrichener releaser and closer component, and a delay time component; said opener component being solenoid actuated, using battery current via the engine starting switch, or latch and ratchet actuated from the preceding warmed-up period of engine operation; said releaser component being a switch, for solenoid actuated openers, or a battery powered solenoid, or a spring loaded intake vacuum actuated dashpot, for latch and ratchet actuated openers; said delay timer component being a bimetallic thermostat heated by battery current via the engine starter switch and the engine ignition points or via the engine starter switch only, to actuate releaser switches or releaser solenoids, or a spring loaded dashpot with check valve and air bleed, or a restrictor passage with or without a vacuum breaker to regulate application of intake vacuum to a dashpot releaser.
 3. A device as described in claim 1 wherein; the choke or enrichener opener component is a solenoid and spring loaded magnetic piston which opens the choke when the solenoid is energized and whose spring acts to close the choke when the solenoid is de-energized, said solenoid being energized by battery current supplied via the engine starting switch and a thermostatic opener switch; the choke or enrichener releaser component is the thermostatic opener switch, held closed by a spring; the delay timer component is a bimetallic strip, heated by battery current via the engine starter switch and the engine ignition points in series, which acts to open the thermostatic opener switch when sufficiently heated.
 4. A device as described in claim 3 wherein the bimetallic strip of the delay timer component is heated by battery current via the engine starter switch only.
 5. A device as described in claim 1, wherein; the choke or enrichener opener component is a hold open ratchet on the choke or enrichener shaft or other actuating piece, engageable with a latch; the choke or enrichener releaser component is a solenoid acting when energized, to disengage the latch, against the latch spring, from the ratchet, energized by battery current supplied via the engine starting switch and a thermostatic closer switch held open by a spring; the delay timer component is a bimetallic strip, heated by battery current via the engine starter switch and the engine ignition points in series, which acts to close the thermostatic closer switch when sufficiently heated.
 6. A device as described in claim 5 wherein the bimetallic strip of the delay timer component is heated by battery current via the engine starter switch only.
 7. A device as described in claim 1, wherein; the choke or enrichener opening component is a solenoid with spring loaded magnetic piston or diaphragm which opens the choke when the solenoid is energized and whose spring acts to close the choke when the solenoid is deenergized, said solenoid being energized by battery current supplied via the engine starting switch and a release switch, held closed by a spring or held open by another solenoid when the latter is energized by battery current supplied via the engine starting switch; the choke or enrichener releaser component is a collar on the piston rod of the magnetic piston or diaphragm which opens the release switch when the choke reaches wide open position; the delay timer component is a check valve and separate air bleed restriction in the magnetic piston or diaphragm or its sealed cylinder end, acting to slow the spring actuated closure of the choke or enrichener.
 8. A device as described in claim 1, wherein; the choke or enrichener opener component is a hold open ratchet on the choke or enrichener shaft or other actuating part, engageable with a latch; the choke or enrichener releaser component is a solenoid acting, when energized, to disengage the latch, against the latch spring, from the ratchet, energized by battery current supplied via the engine starting switch; the delay timer component is a check valve and separate air bleed restriction in a spring loaded diaphragm, bellows, or piston, or its sealed cylinder end, on the choke actuating link, acting to slow the spring actuated motion of the piston, diaphragm, or bellows, to close the choke or enrichener.
 9. A device as described in claim 1, wherein; the choke or enrichener opener component is a hold open ratchet on the choke or enrichener shaft or other actuating part, engageable with a latch; the choke or enrichener releaser component is a dashpot, spring loaded to engage the latch, actuated by an intake manifold vacuum of two to four inches of mercury to disengage the latch from the ratchet, said dashpot consisting of a piston in a cylinder or a sealed diaphragm within a chamber, or a metallic bellows, the sealed volume on the vacuum side of which is connected, via a restrictor passage, to the engine intake manifold, and separately to a vacuum breaker; the delay timer component is the restrictor passage in the intake manifold connection, proportioned to the sealed cylinder or chamber volume on the vacuum side of the releaser dashpot to achieve the desired timer delay.
 10. A device as described in claim 9 wherein the vacuum breaker in the releaser component is a valve, positioned by a bimetallic strip so that the valve is closed when the bimetallic strip is cold and the valve is open when the bimetallic strip is warm, the bimetallic strip being heated by being in contact with a portion of the engine whose temperature increases as the engine warms up, such as the engine jacket, the carburetor, stove, etc.
 11. A device as described in claim 9 wherein the vacuum breaker in the releaser component is a capillary tube, the upper end of which is open to the atmosphere and the lower end of which is submerged into a volume of viscous liquid contained in a sealed chamber whose free space, above the viscous liquid, connects separately to the sealed cylinder or chamber volume on the vacuum side of the releaser dashpot, said chamber and viscous liquid being in contact with a portion of the engine whose temperature increases as the engine warms up, such as the engine jacket, the carburetor stove, etc.
 12. A device as described in claim 9 wherein an additional time delay device is mounted on the choke or enrichener actuating link consisting of a check valve and separate air bleed restriction in a spring loaded diaphragm, bellows, or piston, or its sealed cylinder end, acting to slow the spring actuated motion of the piston, diaphragm, or bellows to close the choke or enrichener.
 13. A device as described in claim 5 wherein an additional time delay device is mounted on the choke or enrichener actuating link consisting of a check valve and separate air bleed restriction in a spring loaded diaphragm, bellows, or piston, or its sealed cylinder end, acting to slow the spring actuated motion of the piston, diaphragm, or bellows to close the choke or enrichener.
 14. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be held fully open and inoperative at the initiation of the cranking of the engine for starting and which then releases said choke plate to close to the extent permitted by the usual automatic or manual choke control, after a delay time interval of engine cranking, the choke plate then becoming operative to enrichen the air fuel mixture in order that the engine may start firing, said device comprising the following listed components: a. A chOke opener component to automatically open and hold fully open the choke plate at the initiation of the cranking of the engine. b. A choke releaser component to automatically release the choke from the fully open position and cause the choke to close the the extent permitted by the usual automatic or manual choke control. c. A delay timer component to automatically set the delay time interval of engine cranking which intervenes between the initiation of the cranking of the engine and the full closure of the choke plate to the extent allowed by the usual automatic or manual choke control.
 15. A device, added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently, after a delay time interval of engine cranking, releases said choke plate which then closes, to the extent permitted by the usual automatic or manual choke control, and becomes operative to enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components: a. A choke opener component to automatically open fully the choke plate at the initiation of the cranking of the engine, the opening being accomplished by a solenoid and magnetic piston, one of which connects to the choke actuating lever and the other of which connects to the usual automatic or manual choke control, the solenoid of which is energized with battery current via the engine starting switch and a choke releaser switch in series therewith, such solenoid energizing causing the magnetic piston to move, against a choke closer spring, to open the choke fully. b. A choke releaser and closer component to automatically release and close the choke, after a delay time interval of engine cranking, the releasing being accomplished by the aforementioned releaser switch in series with the solenoid of the choke opener component so that opening the switch de-energizes said solenoid, the closing being accomplished by the aforementioned choke closer spring acting on the magnetic piston of the choke opener component in a direction to close the choke, said spring being strong enough to close the choke, to the extent allowed by the usual automatic choke control or the usual manual choke control, but being weak enough to be overcome by the force of the aforementioned solenoid acting on the aforementioned magnetic piston. c. A delay timer component to automatically set the delay time interval of engine cranking with the choke fully open so that said time interval increases as ambient air temperature decreases, said delay timer component being a bimetallic thermostat element heated by battery current via the engine starter switch, said bimetallic thermostat element being so positioned that it mechanically opens the choke releaser switch of the aforementioned choke releaser and closer component after being sufficiently heated by said battery current and is thus sufficiently deflected as to open said switch, the required time of heating to switch opening, and thus the delay time interval being longer as the ambient temperature and thus the beginning temperature of the bimetallic thermostat element becomes lower.
 16. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently, after a delay time interval of engine cranking, releases said choke plate which then closes, to the extent permitted by the usual automatic or manual choke control, and becomes operative to enrichen the air-fuel mixture in order that the engine may start firing, said device comprIsing the following listed components: a. A choke opener component to automatically hold fully open the choke plate at the initiation of the cranking of the engine, the holding being accomplished by a magnetic piston and locking bar, spring engaged to a hold open ratchet on the choke shaft so that the choke plate, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after being stopped. b. A choke releaser component to automatically release the choke, after a delay time interval of engine cranking, the releasing being accomplished by energizing a solenoid which is strong enough to move the aforementioned magnetic piston of the choke opener component against the ratchet engaging spring and so disengage the locking bar from the hold open ratchet and thus release the choke plate to close to the extent allowed by the usual automatic choke control or the usual manual choke control, said solenoid being energized from the battery via the engine starter switch and a thermostatic closer switch in series therewith. c. A delay timer component to automatically set the delay time interval of engine cranking with the choke fully open so that said time interval increases as ambient air temperature decreases, said delay timer component being a bimetallic thermostat element heated by battery current via the engine starter switch, said bimetallic thermostat element being so positioned that it mechanically closes the aforementioned thermostatic closer switch of the aforementioned choke releaser component after being sufficiently heated by said battery current and is thus sufficiently deflected as to close said switch, the required time of heating to switch closure, and thus the delay time interval, being longer as the ambient temperature and thus the beginning temperature of the bimetallic thermostat element becomes lower.
 17. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently, after a delay time interval of engine cranking, releases said choke plate which then closes, to the extent permitted by the usual automatic or manual choke control, and becomes operative to enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components: a. A choke opener component to automatically hold fully open the choke plate at the initiation of the cranking of the engine, the holding being accomplished by a piston and locking bar, spring engaged to a hold open ratchet on the choke shaft so that the choke plate, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after being stopped. b. A choke releaser component to automatically release the choke, after a delay time interval of engine cranking, the releasing being accomplished by applying intake manifold craning vacuum via a restricted tube to the closed end of a cylinder, fitted closely around the aforementioned piston of the choke opener component, said closed end being on the piston side opposite the locking bar, in order to move the piston and locking bar against the engaging spring in a direction to disengage the locking bar from the aforementioned hold open ratchet and thus release the choke plate to close to the extent allowed by the usual automatic choke control or the usual manual choke control. The piston area of the cylinder is proportioned so that cranking intake manifold vacuum exerts sufficient net force on the piston to fully overcome the opposite acting force of the engaging spring. c. A delay timer component to automatically set the delay time interval of the engine cranking with the choke fully open, said delay timer component being the restricted tube connecting the closed end of the aforementioned cylinder of the choke releaser component to the engine intake manifold. This restricted tube delays the time of full application of cranking intake manifold vacuum to the piston of the choke opener component until the excess air inside the closed end of the cylinder has flowed through the restricted tube into the intake manifold. The delay time interval of engine cranking can thus be set to the desired value by adjusting the air volume in the closed end of the cylinder and the size of the restriction in the restricted tube, said delay time interval being increased by increasing the air volume and by decreasing the size of the restriction.
 18. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently releases said choke plate which then closes slowly, to the extent permitted by the usual automatic or manual choke control, and becomes operative to gradually enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components: a. A choke opener component to automatically open fully the choke plate at the initiation of the cranking of the engine, the opening being accomplished by a solenoid with a cylindrical core cavity and a magnetic piston fitted closely to the interior of said cylindrical core cavity one of which connects to the choke actuating lever and the other of which connects to the usual automatic or manual choke control, the solenoid of which is energized with battery current via the engine starter switch and a solenoid release switch in series therewith, such solenoid energizing causing the magnetic piston to move within the cylindrical core cavity of the solenoid, against a choke closer spring, to open the choke plate fully. b. A choke releaser component to automatically release the choke, the releasing being accomplished by a member, integral with the connection between the choke opener component and the choke actuating lever, which mechanically moves the magnetic switch bar of the aforementioned solenoid release switch against the hold closed spring of the switch and into magnetic contact with a hold open solenoid, said hold open solenoid being energized with battery current via the engine starter switch and having sufficient magnetic field strength, when energized, to hold the magnetic switchbar in magnetic contact with itself against the contrary force of the hold closed spring, said movement of the magnetic switch bar causing the solenoid release switch to open and de-energize the solenoid of the choke opener component, and thus release the choke plate to close slowly to the extent allowed by the usual automatic choke control or the usual manual choke control. c. A delay timer component to automatically set the rate of closing of the choke plate after it has been released by the choke releaser component comprising; the aforementioned choke closer spring, acting between the cylindrical core cavity of the solenoid and the magnetic piston of the choke opener component in a direction to close the choke plate; the aforementioned magnetic piston fitted with a restricted passage between the faces of the piston and an open passage between these piston faces containing a check valve which closes said open passage whenever the magnetic piston is moved by the choke closer spring in the choke closing direction; the aforementioned cylindri-cal core cavity, whose end, toward which the piston moves when opening the choke is atmospherically vented and whose opposite end is closed such that air is trapped in this closed end of the cylindrical core cavity by the closing of the check valve in the open passage of the magnetIc piston. This trapped air can only escape via the restricted passage in the magnetic piston, the rate of such escape of trapped air, and hence the rate of closing of the choke being determined by the diameter of the magnetic piston, the strength of the choke closer spring and the size of the restricted flow passage.
 19. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently releases said choke plate which then closes slowly, to the extent permitted by the usual automatic or manual choke control, and becomes operative to gradually enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components: a. A choke opener component to automatically hold fully open the choke plate at the initiation of the crank-ing of the engine, the holding being accomplished by a magnetic piston and locking bar, spring engaged to a hold open ratchet on the choke shaft so that the choke plate, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after being stopped. b. A choke releaser component to automatically release the choke, the releasing being accomplished by energizing a solenoid which is strong enough to move the aforementioned magnetic piston of the choke opener component against the ratchet engaging spring and so disengage the locking bar from the hold open ratchet and thus release the choke plate to close slowly to the extent allowed by the usual automatic choke control or the usual manual choke control, said solenoid being energized from the battery via the engine starter switch. c. A delay timer component to automatically set the rate of closing of the choke plate after it has been released by the choke releaser component comprising a choke closer dashpot element interposed between the choke actuating lever and the usual automatic or manual choke control. This dashpot contains a choke closer spring acting between a hollow cylinder and a piston fitted closely to the interior of said cylinder in a direction to close the choke. The cylinder of said dashpot is atmospherically vented at the end toward which the piston moves when opening the choke and is closed off at the opposite end. The cylinder and the piston of said dashpot connect to the choke actuating lever and the usual automatic or manual choke control in any order desired. The choke closer dashpot piston contains a restricted flow passage and an open flow passage between the piston faces, the open flow passage being fitted with a check valve which closes when the choke closer spring moves the piston toward the closed end of the cylinder. The air thus trapped in the closed end of the cylinder escapes slowly via the restricted flow passage and thus the piston and the choke plate move slowly in the choke closing direction. The rate of such choke closure can be predetermined by proper selection of the piston diameter, the strength of the choke closer spring and the size of the restricted flow passage. A slower rate of choke closure can be obtained by increasing the piston diameter, by reducing the strength of the choke closer spring and by reducing the size of the restricted flow passage.
 20. A device added to the usual automatic choke control or the usual manual choke control and the choke actuating lever of the choke plate of a gasoline engine carburetor, which causes said choke plate to be automatically held fully open and inoperative at the initiation of the cranking of the engine for starting and which subsequently releases said choke plate which then closes slowly to the extent permitted by the usual automatic or manual choke control, and becomes operative to gradUally enrichen the air-fuel mixture in order that the engine may start firing, said device comprising the following listed components: a. A choke opener component to automatically hold fully open the choke plate at the initiation of the cranking of the engine, the holding being accomplished by a piston and locking bar, spring engaged to a hold open ratchet on the choke shaft so that the choke plate, having been fully opened by the last preceding period of warm operation of the engine, is held fully open while the engine cools down after being stopped. b. A choke releaser component to automatically release the choke, after a delay time interval of engine cranking, the releasing being accomplished by applying intake manifold cranking vacuum via a restricted tube to the closed end of a cylinder, fitted closely around the aforementioned piston of the choke opener component, said closed end being on the piston side opposite the locking bar, in order to move the piston and locking bar against the engaging spring in a direction to disengage the locking bar from the aforementioned hold open ratchet and thus release the choke plate to close to the extent allowed by the usual automatic or manual choke control. The piston area and hence the cross sectional area of the cylinder is proportioned so that cranking intake manifold vacuum exerts sufficient net force on the piston to fully overcome the opposite acting force of the engaging spring. c. A primary delay timer component to automatically set the delay time interval of engine cranking with the choke fully open, said primary delay timer component being the restricted tube commecting the closed end of the aforementioned cylinder of the choke releaser component to the engine intake manifold. This restricted tube delays the time of full application of cranking intake manifold vacuum to the piston of the choke opener component until the excess air inside the closed end of the cylinder has flowed through the restricted tube into the intake manifold. The primary delay time interval of engine cranking can thus be set to the desired value by adjusting the air volume in the closed end of the cylinder and the size of the restriction in the restricted tube, said primary delay time interval being increased by increasing the air volume and by decreasing the size of the restriction. d. A secondary delay timer component to automatically set the rate of closing of the choke plate after it has been released by the choker releaser component comprising a choke closer dashpot element interposed between the choke actuating lever and the usual automatic or manual choke control. This dashpot contains a choke closer spring acting between a hollow cylinder, and a piston fitted closely to the interior of said cylinder in a direction to close the choke. The cylinder of said dashpot is atmospherically vented at the end toward which the piston moves when opening the choke and is closed off at the opposite end. The cylinder and the piston of said dashpot connect to the choke actuating lever and the usual automatic or manual choke control in any order desired. The choke closer dashpot piston contains an open flow passage between the piston faces which is closed by a check valve when the choke closer spring moves the piston toward the closed end of the cylinder. The air thus strapped in the closed end of the cylinder escapes slowly via a restricted flow passage and thus the piston and the choke plate move slowly in the choke closing direction. The rate of such choke closure can be predetermined by proper selection of the piston diameter, the strength of the choke closer spring and the size of the restricted flow passage. A slower rate of choke closure can be obtained by increasing the piston diameter, by reducing the strength of the choke closer spring and by reducing the size of the restricted flow passage.
 21. A device as described in claim 15 wherein the heater connections for the heating of the bimetallic thermoStat element of the delay timer component by battery current are made via the engine starter switch and the usual engine ignition points in series therewith.
 22. A device as described in claim 16 wherein the heater connections for the heating of the bimetallic thermostat element of the delay timer component by battery current are made via the engine starter switch and the usual engine ignition points in series therewith.
 23. A device as described in claim 17 wherein the closed end air volume in the cylinder of the choke releaser component is provided with another connection to a viscous vacuum breaker in order to prevent needless wear of the choke releaser component during warm operation of the engine. The viscous vacuum breaker consists of a chamber partially filled with a viscous fluid the chamber having an atmospherically vented capillary tube therein which extends deeply into the viscous fluid. The chamber space above the viscous fluid level connects via a tube to the closed end air volume in the cylinder of the choke releaser component. The chamber of the viscous vacuum breaker is mounted in thermal contact with a part of the engine, such as the jacket water system, whose temperature increases as the engine warms up.
 24. A device as described in claim 20 wherein the closed end air volume in the cylinder of the choke releaser component is provided with another connection to a viscous vacuum breaker in order to prevent needless wear of the choke releaser component during warm operation of the engine. The viscous vacuum breaker consists of a chamber partially filled with a viscous fluid the chamber having an atmospherically vented capillary tube therein which extends deeply into the viscous fluid. The chamber space above the viscous fluid level connects via a tube to the closed end air volume in the cylinder of the choke releaser component. The chamber of the viscous vacuum breaker is mounted in thermal contact with a part of the engine, such as the jacket water system, whose temperature increases as the engine warms up.
 25. A device as described in claim 17 wherein the closed end air volume in the cylinder of the choke releaser component is provided with another connection to a thermostatic vacuum breaker in order to prevent needless wear of the choke releaser component during warm operation of the engine. The thermostatic vacuum breaker consists of a valve positioned by a bimetallic thermostat element in the atmospherically vented end of the tube connecting to the closed end air volume in the cylinder of the choke releaser component. The bimetallic thermostat element is arranged to hold the valve closed when cold but to open the valve when sufficiently heated. The bimetallic thermostat element is mounted in thermal contact with a part of the engine, such as the jacket water system, whose temperature increases as the engine warms up.
 26. A device as described in claim 20 wherein the closed end air volume in the cylinder of the choke releaser component is provided with another connection to a thermostatic vacuum breaker in order to prevent needless wear of the choke releaser component during warm operation of the engine. The thermostatic vacuum breaker consists of a valve positioned by a bimetallic thermostat element in the atmospherically vented end of the tube connecting to the closed end air volume in the cylinder of the choke releaser component. The bimetallic thermostat element is arranged to hold the valve closed when cold but to open the valve when sufficiently heated. The bimetallic thermostat element is mounted in thermal contact with a part of the engine, such as the jacket water system, whose temperature increases as the engine warms up.
 27. A device as described in claim 16 wherein, in addition to the primary delay timer component as described in claim 16, an additional secondary delay timer is incorporated to automatically set the rate of closing of the choke plate after it has been released by the choke releaser component comprising a choke closer dashpot element interposed between the choke actuating lever and the usual automatic or manual choke control. This dashpot contains a choke closer spring acting between a hollow cylinder and a piston fitted closely to the interior of said cylinder in a direction to close the choke. The cylinder of said dashpot is atmospherically vented at the end toward which the piston moves when opening the choke and is closed off at the opposite end. The cylinder and the piston of said dashpot connect to the choke actuating lever and the usual automatic or manual choke control in any order desired. The choke closer dashpot piston contains an open flow passage between the piston faces which is closed by a check valve when the choke closer spring moves the piston toward the closed end of the cylinder. The air thus trapped in the closed end of the cylinder escapes slowly via a restricted flow passage and thus the piston and the chock plate move slowly in the choke closing direction. The rate of such choke closure can be predetermined by proper selection of the piston diameter, the strength of the choke closer spring and the size of the restricted flow passage. A slower rate of choke closure can be obtained by increasing the piston diameter, by reducing the strength of the choke closer spring and by reducing the size of the restricted flow passage. 